Line circuits are frequently used to control traffic direction in a stretch of railroad track where trains move in either direction between stations. Such traffic circuits are especially used where either direction running is used on each track of a double or multi-track railroad between adjacent crossover interlockings. Operation of such traffic circuits must, of couse, be vital to assure that, at any time, only one direction of traffic can be established and, if used that cab signal or train control energy can be supplied in the rails for only one direction of travel. That is, it must be impossible to supply cab signal energy to the rails at one time which would authorize opposing train moves. At the same time, the traffic circuits must be economical in the line wire and relay apparatus required. Such saving in line wire is particularly pertinent where remote controlled electric switch locks are employed on spur tracks between signal locations to protect against inadvertent and unauthorized entry of a train onto the main track. A desirable goal is to also eliminate block directional stick relays at each intermediate location, between the end interlockings, where the detector track circuits are divided or repeated. In other words, it is desirable to establish and hold traffic direction at each intermediate location by the use of a single traffic relay of the so-called polar or magnetic stick type.
Accordingly, an object of my invention is an improved and more economical traffic control circuit for a signal system for a stretch of single track railroad.
Another ojbect of the invention is a two-wire traffic line circuit arrangement for a single track railroad signal system which uses only a single vital magnetic stick relay at each location to establish and hold the selected traffic direction.
A further object of my invention is a traffic control system for a single track stretch of railroad in which a single vital magnetic stick relay at each end and intermediate location establishes and holds the selected traffic direction.
Yet another object of the invention is a reversible traffic line circuit arrangement, for a signal system for a single track stretch of railroad which is divided into a plurality of detector track circuits, each with a corresponding separate reversible traffic line circuit section selectively energized from the desired exit end of the section to energize a direction repeater relay at the entrance end, each location also including a single magnetic stick traffic relay positioned in accordance with the condition of the associated repeater relays to establish and hold the selected traffic direction until a positive action is taken to reverse the traffic direction.
Other objects, features, and advantages of my invention will become apparent from the following specification and appended claims when taken in connection with the accompanying drawings.